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Old 03-08-2019, 06:52 PM   #1
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Portable Solar Panel: Real Testing

I posted this huge write up on another forum few months ago and I thought some of you might benefit from our testing. It is really a pain to post pictures here so there wont be any in this post.

Full Post is here: https://www.expeditionportal.com/for.../#post-2565501

For a full video of the results you can go here:

I know that I will probably offend some of the panel manufacturers with this testing. I believe that the results would be useful to those that are seeking to purchase panels in the future or simply want to know why their panels are not performing as anticipated.

I will start off here with some background of why I am posting this. Over the last few years we have sold most of the major bands of fixed and portable panels to our customers with varying results of durability and output. Each panel had its strengths and weaknesses. Some panels were super portable but lacked the output and some panels were large and bulky but had reasonable output. The one thing that almost all of them had in common was that the all seemed to not produce their stated power. As an engineer I really want to dig down to the bottom of it and find out why.

The first set of benchmark tests was relatively easy. Simply stated, put the panel in the sun and test its actual output and compare that to its stated rating. After doing the field testing I realized that some more in depth lab testing was needed to figure out why some of the panels fell short. We did a whole host of lab tests on each panel in a real solar lab, yep a real deal solar lab. If we are going to do the testing we should do it right. Each panel was even dismantled to test the solder joints and connections. I will do another post on portable panel construction in the near future to address those issues also. The one test that stood out the most as to why some panels performed poorly was the electroluminscence testing. For results please read on.

Panels To Be Tested- All of the panels are brand new and have not been used except for this testing.
1) Overland Solar 120 Watt: Sunpower mono-crystalline cell, busbar, soldered wire connections between panes

2) Flexopower 105 Watt: Solarworld mono-crystalline cell, busbar, soldered wire connections between panes

3) GoPower 100 Watt Flexible Panel: Sunpower mono-crystalline cell, busbar
4) Merlin Solar 160 Watt: Mono PERC CSi, Merlin Grid, solid copper band between panes

5) GoPower 100 Watt Glass Panel (reference panel): Carmana mono-crystalline cell. Not a portable panel but by far and away the most prolific panel on the market.

Test Method-
1) Place the panels at the same angle on the test jig facing the sun and measure the power coming out of the panel using a Thornwave Blutoooth PowerMon. We want to measure at the panel to limit any influence that the MPPT may have. (As a side note If you guys have not heard of this the Thornwave Blutoooth PowerMon then you are really missing out. It is has a 60 amp current shunt or you can attach up to 1000 amp current shunt. Bluetooth, control relays, monitor power etc, it can also control the charging from your vehicle to any type of battery.)

2) The panels will be fed into a Redarc BCDC1240D, 40 amp DC-DC and MPPT solar controller

3) The Redarc will then feed the power into two 100Ah lithium batteries. It is a battery bank that we made up for us to use at shows and around the shop and will be perfect for this testing.

4) A constant load will be applied to the the batteries in the form of two 12V led light bars so that the panels will be working at their peak output. Everyone knows that solar panels do not work well when the battery is full.

5) Each panels will be tested 3 times at a random selection to mitigate the variability in the angle of the sun. No clouds were present when testing.

Test Condition:
Temp: 42°F
Sun: Approx 10:00-11:00 AM

Field Testing and Results:

Portable Panel Results: The Merlin Solar panel exceeded the stated rating by 10%. It is rated at 160 watts and it produce 176.15 watts. That is incredible considering we did not have lab level conditions for the field testing. The next closest panels in the portable category was the Flexible 100 Watt panel. It is rated at 100 watts and it produce 98.53 watts. Much father down the line were the Overland Solar 120 watt panel and the Flexopower 105 watt panel. Neither one reached its rated output.

Fixed Panel Result: There was really no surprise here. The glass panels performed as it show just barely beating its rated power of 100 watts.
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